349 research outputs found

    Pressure evolution of electron dynamics in the superconducting kagome metal CsV3_3Sb5_5

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    The coexistence of the charge-density wave (CDW) and superconducting phases and their tunability under external pressure remains one of the key points in understanding the electronic structure of AAV3_3Sb5_5 (AA = K, Rb, Cs) kagome metals. Here, we employ synchrotron-based infrared spectroscopy assisted by density-functional calculations to study the pressure evolution of the electronic structure at room temperature up to 17 GPa experimentally. The optical spectrum of CsV3_3Sb5_5 is characterized by the presence of localized carriers seen as a broad peak at finite frequencies in addition to the conventional metallic Drude response. The pressure dependence of this low-energy peak reflects the re-entrant behavior of superconductivity and may be interpreted in terms of electron-phonon coupling, varying with the growth and shrinkage of the Fermi surface. Moreover, drastic modifications in the low-energy interband absorptions are observed upon the suppression of CDW. These changes are related to the upward shift of the Sb2 px+pyp_x+p_y band that eliminates part of the Fermi surface around the MM-point, whereas band saddle points do not move significantly. These observations shed new light on the mixed electronic and lattice origin of the CDW in CsV3_3Sb5_5

    Preclinical Incorporation Dosimetry of [18F]FACH—A Novel 18F-Labeled MCT1/MCT4 Lactate Transporter Inhibitor for Imaging Cancer Metabolism with PET

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    Overexpression of monocarboxylate transporters (MCTs) has been shown for a variety of human cancers (e.g., colon, brain, breast, and kidney) and inhibition resulted in intracellular lactate accumulation, acidosis, and cell death. Thus, MCTs are promising targets to investigate tumor cancer metabolism with positron emission tomography (PET). Here, the organ doses (ODs) and the effective dose (ED) of the first 18F-labeled MCT1/MCT4 inhibitor were estimated in juvenile pigs. Whole-body dosimetry was performed in three piglets (age: ~6 weeks, weight: ~13–15 kg). The animals were anesthetized and subjected to sequential hybrid Positron Emission Tomography and Computed Tomography (PET/CT) up to 5 h after an intravenous (iv) injection of 156 ± 54 MBq [18F]FACH. All relevant organs were defined by volumes of interest. Exponential curves were fitted to the time–activity data. Time and mass scales were adapted to the human order of magnitude and the ODs calculated using the ICRP 89 adult male phantom with OLINDA 2.1. The ED was calculated using tissue weighting factors as published in Publication 103 of the International Commission of Radiation Protection (ICRP103). The highest organ dose was received by the urinary bladder (62.6 ± 28.9 µSv/MBq), followed by the gall bladder (50.4 ± 37.5 µSv/MBq) and the pancreas (30.5 ± 27.3 µSv/MBq). The highest contribution to the ED was by the urinary bladder (2.5 ± 1.1 µSv/MBq), followed by the red marrow (1.7 ± 0.3 µSv/MBq) and the stomach (1.3 ± 0.4 µSv/MBq). According to this preclinical analysis, the ED to humans is 12.4 µSv/MBq when applying the ICRP103 tissue weighting factors. Taking into account that preclinical dosimetry underestimates the dose to humans by up to 40%, the conversion factor applied for estimation of the ED to humans would rise to 20.6 µSv/MBq. In this case, the ED to humans upon an iv application of ~300 MBq [18F]FACH would be about 6.2 mSv. This risk assessment encourages the translation of [18F]FACH into clinical study phases and the further investigation of its potential as a clinical tool for cancer imaging with PET

    The Case for a Muon Collider Higgs Factory

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    We propose the construction of a compact Muon Collider Higgs Factory. Such a machine can produce up to \sim 14,000 at 8\times 10^{31} cm^-2 sec^-1 clean Higgs events per year, enabling the most precise possible measurement of the mass, width and Higgs-Yukawa coupling constants.Comment: Supporting letter for the document: "Muon Collider Higgs Factory for Smowmass 2013", A White Paper submitted to the 2013 U.S. Community Summer Study of the Division of Particles and Fields of the American Physical Society, Y. Alexahin, et. al, FERMILAB-CONF-13-245-T (July, 2013

    Balancing economic and ecological functions in smallholder and industrial oil palm plantations

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    The expansion of the oil palm industry in Indonesia has improved livelihoods in rural communities, but comes at the cost of biodiversity and ecosystem degradation. Here, we investigated ways to balance ecological and economic outcomes of oil palm cultivation. We compared a wide range of production systems, including smallholder plantations, industrialized company estates, estates with improved agronomic management, and estates with native tree enrichment. Across all management types, we assessed multiple indicators of biodiversity, ecosystem functions, management, and landscape structure to identify factors that facilitate economic-ecological win-wins, using palm yields as measure of economic performance. Although, we found that yields in industrialized estates were, on average, twice as high as those in smallholder plantations, ecological indicators displayed substantial variability across systems, regardless of yield variations, highlighting potential for economic-ecological win-wins. Reducing management intensity (e.g., mechanical weeding instead of herbicide application) did not lower yields but improved ecological outcomes at moderate costs, making it a potential measure for balancing economic and ecological demands. Additionally, maintaining forest cover in the landscape generally enhanced local biodiversity and ecosystem functioning within plantations. Enriching plantations with native trees is also a promising strategy to increase ecological value without reducing productivity. Overall, we recommend closing yield gaps in smallholder cultivation through careful intensification, whereas conventional plantations could reduce management intensity without sacrificing yield. Our study highlights various pathways to reconcile the economics and ecology of palm oil production and identifies management practices for a more sustainable future of oil palm cultivation.</p

    Second Generation Leptoquark Search in p\bar{p} Collisions at s\sqrt{s} = 1.8 TeV

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    We report on a search for second generation leptoquarks with the D\O\ detector at the Fermilab Tevatron ppˉp\bar{p} collider at s\sqrt{s} = 1.8 TeV. This search is based on 12.7 pb1^{-1} of data. Second generation leptoquarks are assumed to be produced in pairs and to decay into a muon and quark with branching ratio β\beta or to neutrino and quark with branching ratio (1β)(1-\beta). We obtain cross section times branching ratio limits as a function of leptoquark mass and set a lower limit on the leptoquark mass of 111 GeV/c2^{2} for β=1\beta = 1 and 89 GeV/c2^{2} for β=0.5\beta = 0.5 at the 95%\ confidence level.Comment: 18 pages, FERMILAB-PUB-95/185-

    Analysis of a Panel of 48 Cytokines in BAL Fluids Specifically Identifies IL-8 Levels as the Only Cytokine that Distinguishes Controlled Asthma from Uncontrolled Asthma, and Correlates Inversely with FEV1

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    We sought to identify cells and cytokines in bronchoalveolar lavage (BAL) fluids that distinguish asthma from healthy control subjects and those that distinguish controlled asthma from uncontrolled asthma. Following informed consent, 36 human subjects were recruited for this study. These included 11 healthy control subjects, 15 subjects with controlled asthma with FEV1≥80% predicted and 10 subjects with uncontrolled asthma with FEV1 2.4%) were a higher BAL fluid IL-8 levels, and a lower FEV1 in the latter group. By contrast, compared to eosinophil-normal asthma (eosinophils≤0.3%), eosinophil-high asthma (eosinophils>0.3%) had higher levels of IL-5, IL-13, IL-16, and PDGF-bb, but same neutrophil percentage, IL-8, and FEV1. Our results identify neutrophils and IL-8 are the only inflammatory components in BAL fluids that distinguish controlled asthma from uncontrolled asthma, and both correlate inversely with FEV1

    Model-based assessment of mammalian cell metabolic functionalities using omics data.

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    Omics experiments are ubiquitous in biological studies, leading to a deluge of data. However, it is still challenging to connect changes in these data to changes in cell functions because of complex interdependencies between genes, proteins, and metabolites. Here, we present a framework allowing researchers to infer how metabolic functions change on the basis of omics data. To enable this, we curated and standardized lists of metabolic tasks that mammalian cells can accomplish. Genome-scale metabolic networks were used to define gene sets associated with each metabolic task. We further developed a framework to overlay omics data on these sets and predict pathway usage for each metabolic task. We demonstrated how this approach can be used to quantify metabolic functions of diverse biological samples from the single cell to whole tissues and organs by using multiple transcriptomic datasets. To facilitate its adoption, we integrated the approach into GenePattern (www.genepattern.org-CellFie)

    Genome-Scale Identification Method Applied to Find Cryptic Aminoglycoside Resistance Genes in Pseudomonas aeruginosa

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    BACKGROUND:The ability of bacteria to rapidly evolve resistance to antibiotics is a critical public health problem. Resistance leads to increased disease severity and death rates, as well as imposes pressure towards the discovery and development of new antibiotic therapies. Improving understanding of the evolution and genetic basis of resistance is a fundamental goal in the field of microbiology. RESULTS:We have applied a new genomic method, Scalar Analysis of Library Enrichments (SCALEs), to identify genomic regions that, given increased copy number, may lead to aminoglycoside resistance in Pseudomonas aeruginosa at the genome scale. We report the result of selections on highly representative genomic libraries for three different aminoglycoside antibiotics (amikacin, gentamicin, and tobramycin). At the genome-scale, we show significant (p<0.05) overlap in genes identified for each aminoglycoside evaluated. Among the genomic segments identified, we confirmed increased resistance associated with an increased copy number of several genomic regions, including the ORF of PA5471, recently implicated in MexXY efflux pump related aminoglycoside resistance, PA4943-PA4946 (encoding a probable GTP-binding protein, a predicted host factor I protein, a delta 2-isopentenylpyrophosphate transferase, and DNA mismatch repair protein mutL), PA0960-PA0963 (encoding hypothetical proteins, a probable cold shock protein, a probable DNA-binding stress protein, and aspartyl-tRNA synthetase), a segment of PA4967 (encoding a topoisomerase IV subunit B), as well as a chimeric clone containing two inserts including the ORFs PA0547 and PA2326 (encoding a probable transcriptional regulator and a probable hypothetical protein, respectively). CONCLUSIONS:The studies reported here demonstrate the application of new a genomic method, SCALEs, which can be used to improve understanding of the evolution of antibiotic resistance in P. aeruginosa. In our demonstration studies, we identified a significant number of genomic regions that increased resistance to multiple aminoglycosides. We identified genetic regions that include open reading frames that encode for products from many functional categories, including genes related to O-antigen synthesis, DNA repair, and transcriptional and translational processes
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